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Previous: 31.7 Categories of Macros Chapter 31
Defined Macros
Next: 31.9 Pitfalls

31.8 Macros with the m4 Technique

The various features of the m4 technique use uppercase single-character macro names. The complete list of them is shown in Table 31.5 . Some of these are defined by using the appropriate define m4 command (see below). Others are predefined for you by the m4 technique. See the appropriate section reference for a full description of how to use each macro.

Table 31.5: Macros Reserved with the m4 Technique
Macro Description
$B Section 31.10.5, $B The BITNET relay
$C Section 31.10.9, $C The hostname of the DECnet relay
$E Section 31.10.13, $E X.400 relay (unused)
$F Section 31.10.15, $F FAX relay
$H Section 31.10.18, $H The mail hub
$L Section 31.10.23, $L Unknown Local User relay
$M Section 31.10.25, $M Who we are masquerading as
$R Section 31.10.32, $R The relay for unqualified names (deprecated)
$S Section 31.10.34, $S The Smart Host
$U Section 31.10.37, $U The UUCP name to override $k
$V Section 31.10.39, $V The UUCP relay (for class $=V )
$W Section 31.10.41, $W The UUCP relay (for class $=W )
$X Section 31.10.43, $X The UUCP relay (for class $=X )
$Y Section 31.10.45, $Y The UUCP relay for unclassified hosts
$Z Section 31.10.47, $Z The version of this m4 configuration

A few m4 macros can be defined by using the m4 define command. For example, here is how you define the BITNET relay with the BITNET_RELAY keyword:

define(`BITNET_RELAY', `



See Table 31.6 for a list of those m4 macros that can be defined. The leftmost column in that table shows the keyword to use.

Table 31.6: Macros Declared with Special m4 Names
m4 name Macro Description
BITNET_RELAY $B Section 31.10.5 The BITNET relay
confCF_VERSION $Z Section 31.10.47 The version of this m4 configuration
confDOMAIN_NAME $j Section 31.10.20 Official canonical name
confMAILER_NAME $n Section 31.10.26 Error message sender
FAX_RELAY $F Section 31.10.15 FAX relay
LUSER_RELAY $L Section 31.10.23 Local user relay
MAIL_HUB $H Section 31.10.18 The mail hub